The subject matter disclosed herein generally relates to elevator systems. More specifically, the subject disclosure relates to guide rails used in elevator systems for elevator cars and counterweights.
Elevator systems typically include an elevator car suspended in a hoistway by a number of suspension ropes or belts, and a counterweight suspended by the ropes or belts to balance the elevator system. The counterweight and elevator car each are guided by guide rails fixed in the hoistway.
The elevator car is connected to the car guide rails via one or more car guide shoes such that the elevator car follows a path defined by the car guide rails as it moves through the hoistway. Further, in some elevator systems, an emergency braking mechanism connected to the elevator car acts on the car guide rails to slow and/or stop the elevator car in the hoistway. Similarly, the counterweight includes one or more counterweight guide shoes to guide the counterweight along a path defined by the counterweight guide rails.
The typical car guide rail is a solid steel T-shaped rail. Such rail configurations are typically utilized because of their ability to withstand buckling and deflection during normal elevator operations and to withstand and loads applied during emergency braking. The typical car guide rails, however, are heavy and bulky, with each rail typically weighing 8 kilograms or more per meter and are typically installed in sections of 5 meters in length. Further, the amount of material used to form the rail drives the rail cost upward.
Sheet metal rails require less material and thus are less costly and lighter weight than traditional solid steel rail. Such rails have been utilized as counterweight guide rails, but not as elevator car guide rails because of the failure of such rail configurations to have the required torsional stiffness and crush resistance during operation of the elevator system and during emergency braking of the elevator car.